Ballet Abs - I don't remember doing any of these separately (except for crunches) when I use to dance. I got my "ballet abs" by holding it in during class for 10 years; however, these exercises are great for anyone.
Get it done in seven minutes a day. This 7 minute HIIT body weight workout does more than just scorching calories during the session, but long hours after. Plus you get both cardio and strength training at the same time.